"""海报后台任务管理。

使用与 PPT parse_worker 相同的后台线程 + Redis 锁模式。
任务状态通过数据库字段追踪，前端轮询获取进度。
"""
import json
import logging
import threading
import os
from datetime import datetime

from insurance.db.compat import db

logger = logging.getLogger(__name__)

_local_locks: set = set()
_local_locks_guard = threading.Lock()
_redis_locks: set = set()

# 超过此时间仍为 queued/generating 的任务视为过期（秒）
STALE_TASK_TIMEOUT = 600  # 10 分钟


def recover_stale_tasks():
    """启动时恢复过期任务：将长时间 queued/generating 的任务标记为 failed。

    应在应用启动时调用。
    """
    from insurance.models.poster_record import PosterRecord
    from insurance.models.poster_case_upload import PosterCaseUpload

    cutoff = datetime.now().timestamp() - STALE_TASK_TIMEOUT

    # 恢复过期的海报生成任务
    stale_records = PosterRecord.query.filter(
        PosterRecord.task_status.in_(["queued", "generating"]),
        PosterRecord.created_at < datetime.fromtimestamp(cutoff),
    ).all()
    for record in stale_records:
        record.task_status = "failed"
        record.task_error = "任务因服务重启而中断，请重新生成"
        record.finished_at = datetime.now()
        logger.warning(f"恢复过期海报任务: record_id={record.id}")

    # 恢复过期的计划书解析任务
    stale_cases = PosterCaseUpload.query.filter(
        PosterCaseUpload.parse_status.in_(["queued", "parsing"]),
        PosterCaseUpload.created_at < datetime.fromtimestamp(cutoff),
    ).all()
    for case in stale_cases:
        case.parse_status = "failed"
        logger.warning(f"恢复过期解析任务: case_id={case.id}")

    if stale_records or stale_cases:
        db.session.commit()
        logger.info(f"已恢复 {len(stale_records)} 个海报任务, {len(stale_cases)} 个解析任务")


# ─── 计划书解析任务 ───────────────────────────────────────

def start_case_parse_task(app, case_upload_id: int) -> bool:
    """启动后台计划书解析任务，返回是否新启动。"""
    lock_key = f"poster_case_parse:{case_upload_id}"
    if not _acquire_lock(lock_key):
        return False

    thread = threading.Thread(
        target=_run_case_parse_task,
        args=(app, case_upload_id, lock_key),
        daemon=True,
    )
    thread.start()
    return True


def _run_case_parse_task(app, case_upload_id: int, lock_key: str):
    with app.app_context():
        try:
            _execute_case_parse(case_upload_id)
        except Exception as exc:
            logger.error(f"计划书解析任务失败 [{case_upload_id}]: {exc}", exc_info=True)
            _mark_case_failed(case_upload_id, str(exc))
        finally:
            _release_lock(lock_key)
            db.session.remove()


def _execute_case_parse(case_upload_id: int):
    from insurance.models.poster_case_upload import PosterCaseUpload

    record = PosterCaseUpload.query.get(case_upload_id)
    if not record:
        return

    filepath = record.source_file_url
    if not filepath or not os.path.exists(filepath):
        record.parse_status = "failed"
        db.session.commit()
        return

    record.parse_status = "parsing"
    db.session.commit()

    from insurance.ppt.extraction import ExtractionOrchestrator
    orchestrator = ExtractionOrchestrator(use_cache=False)

    import asyncio
    parsed = asyncio.run(orchestrator.extract_for_poster(filepath))

    record = PosterCaseUpload.query.get(case_upload_id)
    if not record:
        return
    record.parsed_data = json.dumps(parsed, ensure_ascii=False)
    record.parse_status = "parsed"
    db.session.commit()


def _mark_case_failed(case_upload_id: int, error: str):
    from insurance.models.poster_case_upload import PosterCaseUpload

    record = PosterCaseUpload.query.get(case_upload_id)
    if not record:
        return
    record.parse_status = "failed"
    db.session.commit()


# ─── 锁管理 ────────────────────────────────────────────────

def _acquire_lock(key: str) -> bool:
    """获取任务锁（优先 Redis，降级本地内存）。"""
    redis_key = f"poster_task_lock:{key}"
    try:
        from insurance.db.compat import redis_client
        if redis_client and redis_client.set(redis_key, "1", nx=True, ex=1800):
            _redis_locks.add(key)
            return True
        if redis_client:
            return False
    except Exception:
        pass

    with _local_locks_guard:
        if key in _local_locks:
            return False
        _local_locks.add(key)
        return True


def _release_lock(key: str):
    """释放任务锁。"""
    if key in _redis_locks:
        try:
            from insurance.db.compat import redis_client
            if redis_client:
                redis_client.delete(f"poster_task_lock:{key}")
        except Exception:
            pass
        _redis_locks.discard(key)

    with _local_locks_guard:
        _local_locks.discard(key)